Merge pull request katef#493 from katef/sv/bugfix-endid-qsort-count

bugfix: fsm_endid_get should sort with result count, not buffer size.

src/libfsm/endids.c

@@ -689,6 +689,7 @@ fsm_endid_get(const struct fsm *fsm, fsm_state_t end_state,
 {
 	size_t i;
 	const struct endid_info *ei = NULL;
+	size_t result_count = 0;
 
 	uint64_t hash = hash_id(end_state);
 	uint64_t mask;
@@ -735,9 +736,10 @@ fsm_endid_get(const struct fsm *fsm, fsm_state_t end_state,
 #endif
 				ids[id_i] = b->ids->ids[id_i];
 			}
+			result_count = b->ids->count;
 
 			/* sorting for caller convenience */
-			qsort(ids, count, sizeof *ids, cmp_endids);
+			qsort(ids, result_count, sizeof *ids, cmp_endids);
 
 			return 1;
 		} else {	/* collision */

tests/endids/endids_reused_buffer.c

@@ -0,0 +1,57 @@
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <errno.h>
+
+#include <assert.h>
+
+#include <re/re.h>
+
+#include <fsm/fsm.h>
+#include <fsm/bool.h>
+#include <fsm/pred.h>
+#include <fsm/print.h>
+#include <fsm/walk.h>
+
+#include "endids_utils.h"
+
+/* Test that providing an overly large endid buffer doesn't clobber the result with stale data. */
+int main(void)
+{
+	const char *input = "banana turtle";
+
+	const char *s = input;
+	struct fsm *fsm = re_comp(RE_NATIVE, fsm_sgetc, &s, NULL, 0, NULL);
+	int ret;
+
+	ret = fsm_setendid(fsm, (fsm_end_id_t) 12345);
+	assert(ret == 1);
+
+        ret = fsm_determinise(fsm);
+        assert(ret == 1);
+
+        ret = fsm_minimise(fsm);
+        assert(ret == 1);
+
+	fsm_state_t end;
+	ret = fsm_exec(fsm, fsm_sgetc, &input, &end, NULL);
+	assert(ret == 1);
+
+	const size_t endid_count = fsm_endid_count(fsm, end);
+	assert(endid_count == 1);
+
+	/* Regression: fsm_endid_get previously qsort'd endids with
+	 * a count based on the buffer size (here ENDID_BUF_CEIL),
+	 * rather than the number of results populated, so if the
+	 * buffer was larger than fsm_endid_count's result stale
+	 * contents could displace the correct results. */
+#define ENDID_BUF_CEIL 10
+	fsm_end_id_t endids[ENDID_BUF_CEIL] = { 333 };
+	ret = fsm_endid_get(fsm, end, ENDID_BUF_CEIL, endids);
+	assert(endids[0] == 12345);
+
+	fsm_free(fsm);
+	return EXIT_SUCCESS;
+}